Tonic convulsions are sharp and prolonged muscle contractions, in which the limb or the whole body freezes in a forced position. They are local and generalized, accompanied by pain, dysfunction of other systems. Convulsions manifest infectious diseases, metabolic disorders, intoxications, etc. Neurological examination, laboratory tests (general, biochemical, molecular genetic), functional methods help to find out the cause. Treatment is aimed at relieving symptoms and correcting the underlying pathology.